Certain operating conditions, such as those encountered in a mine haulage truck, require a fire protection system that provides an operator with an immediate indication of the existence of a fire and that can do this with a high degree of reliability. In the case of a mine haulage truck, the operator is located 10 or more feet above the ground and safety requires that he be able to extinguish a fire quickly, or that he at least be warned in time so that he can leave the vehicle before a given danger level is reached. While conventional alarm systems provide some of the necessary features to satisfy the rigid requirements set forth above, none provide the necessary combination of high reliability automatic operation together with suitable operator control so as to insure driver safety.